1. Technical Field
The present invention relates to a projector.
2. Related Art
These days, image quality improvement in electronic display apparatuses such as an LCD (Liquid Crystal Display), an EL (Electro-luminescence) display, a plasma display, a CRT (Cathode Ray Tube), and a projector is remarkable and performance comparable to the human visual properties is being realized with respect to resolution and color gamut. However, with respect to the brightness dynamic range, its reproduced range remains on the order of 1 to 102 [nit], and further, the number of gradations is generally 8 bits. On the other hand, the human visual perception provides a brightness dynamic range that can be perceived at a time on the order of 10−2 to 104 [nit], and further, the brightness discriminative ability is on the order of 0.2 [nit]. This is said to be equal to 12 bits in terms of number of gradations. Seeing a display image of a current display apparatus through such visual properties, the human does not satisfy the reality and impact of the display image because the narrowness of the brightness dynamic range stands out and additionally, the gradations in shadow parts and highlight parts are insufficient.
Further, in computer graphics (CG) used for movies or games, the movement for pursuing description reality by providing display data (hereinafter, referred to as “HDR (High Dynamic Range) display data”) with brightness dynamic range and gradation characteristics close to human visual perception is becoming the mainstream. However, there is a problem that powers of expression the CG contents originally have can not be exerted sufficiently because the performance of the display apparatus for displaying CG is insufficient.
Furthermore, in the next OS (Operative System), 16-bit color space is planned to be adopted, and the brightness dynamic range and the number of gradations will be increased dramatically compared to those in the current 8-bit color space. Accordingly, the demand for realization of an electronic display apparatus with high dynamic range and high gradation capable of utilizing the 16-bit color space is expected to be increased.
Among display apparatuses, projection display apparatuses (projectors) such as a liquid crystal projector and DLP (Digital Light Processing, registered trademark) projector can perform large screen display and are effective display apparatuses for reproducing the reality and impact of display images. In this field, the following proposals have been made in order to solve the above described problems.
As a display apparatus with high dynamic range, for example, there is a technology disclosed in JP-T-2004-523001 and JP-A-2001-100689. In the technology, a light source, a second light modulation device for modulating brightness of all wavelength regions of light, and a first light modulation device for modulating the brightness of the wavelength regions with respect to respective wavelength regions of RGB three primary colors of the wavelength regions of light are provided for forming a desired brightness distribution by modulating light from the light source by the second light modulation device, imaging the optical image thereof onto a display surface of the first light modulation device and performing color modulation, and projecting the secondarily modulated light. The respective pixels of the second light modulation device and the first light modulation device are separately controlled based on the first control value and the second control value determined from the HDR display data, respectively. As the light modulation device, a transmissive modulation device having a pixel structure or segment structure with independently controllable transmittances and capable of controlling a two-dimensional transmittance distribution is used. As a representative example thereof, a liquid crystal light valve is cited. Further, a reflective modulation device may be used in place of the transmissive modulation device, and as a representative example thereof, a micromirror array device is cited.
Now, the case of using a light modulation device having a transmittance of 0.2% of dark display and a transmittance of 60% of light display is considered. Regarding the light modulation device alone, the brightness dynamic range is 60/0.2=300. The display apparatus corresponds to the case where light modulation devices having the brightness dynamic range of 300 are optically and serially arranged, and thereby, the brightness dynamic range of 300×300=90000 can be realized. Further, the equal way of thinking is held with respect to the number of gradations, and the number of gradations exceeding 8 bits can be obtained by optically and serially arranging light modulation devices with 8-bit gradation.
By the way, in a projector with high dynamic range, light is modulated by serially provided two light modulation devices, and a problem that the amount of light finally output from projecting means becomes smaller and the brightness of the display image becomes lower arises. At present, it is assumed that the projector with high dynamic range is used when image display is mainly performed in dark environments as is the case of cinema contents or the like. Accordingly, the above described brightness reduction of display image due to serially provided two light modulation devices is not so much acknowledged as a problem.
However, in the future, there is a possibility that the projector with high dynamic range is used when image display is performed in bright environments as is the case of data contents or the like. In this case, the brightness of display image is likely to be insufficient by the brightness reduction of display image due to serially provided two light modulation devices.